Question

If w = 10 units, x = 5 units, and y = 6 units, what is the surface area of the figure? Round your answer to the nearest tenth.

Figure is composed of a right square pyramid on top of a square prism. The sides of the square pyramid are equal to the sides of the square prism, the length and width of the square prism is w, the height of the square prism is x, and the height of the square pyramid, which forms a right angle with the center, is y.
A) 656.2 units2
B) 400 units2
C) 256.2 units2
D) 456.2 units2

Answer 1

456.2 units², so answer d

Explanation:

The area of the square base is ...

base area = w² = (10 units)² = 100 units²

The lateral area is 4 times the area of one rectangular face:

lateral area = 4wx = 4(10 units)(5 units) = 200 units²

The area of one triangular face is half the product of its base length (w) and its slant height (h). The latter is found using the Pythagorean theorem:

h² = y² +(w/2)² = (6 units)² +((10 units)/2)² = 61 units²

h = √61 units

So, the area of 4 triangles is ...

area of triangular faces = 4(1/2)wh = 2(10 units)(√61 units) ≈ 156.2 units²

Now we have the areas of the parts, so we can add them together to get the total surface area:

surface area = base area + lateral area + area of triangular faces

= 100 units² + 200 units² + 156.2 units²

surface area = 456.2 units²